Pioneer 10 was the first spacecraft to travel beyond Mars to the outer planets of our solar system. During the 21-month, 620-million-mile journey to Jupiter, Pioneer penetrated the previously unexplored asteroid belt without mishap, eliminating the long held fear that high-speed particles or huge asteroids might destroy the spacecraft. This film tells of the findings recorded by the scientific instruments and cameras onboard. After leaving the Jovian system, Pioneer will be on a course that will take the spacecraft out of our solar system where it will wander endlessly through the Milky Way Galaxy, carrying a message for possible extraterrestrial beings.